JP2001115094A - Method for forming bilayer coated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a coated film excellent in opacifying properties even if the content of a coloring pigment of a hydrophilic coloring coating is small and the thickness of the film is thin, and having hardly reduced physical properties is provided in a bilayer coated film obtained by coating an organic solvent-type hydrophilic coating, a water based coloring coating and a clear coating. SOLUTION: This method for forming the bilayer coating film comprises coating (A) the organic solvent-type hydrophilic coating, (B) the water base coloring coating and (C) the clear coating on a material to be coated, and heating the coated materials to harden the coated film, and the method is characterized in that the hydrophilic coating A contains a neutralized product of a carboxyl group-containing resin having 5-100 acid value, a curing agent, an aluminum powder having <=20 μm average particle diameter, and the coloring pigment, and the content of the aluminum powder is regulated so as to be 0.1-10 pts.wt. based on 100 pts.wt. resin solid components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a multilayer coating film by applying an organic solvent type hydrophilic coating material, an aqueous coloring coating material and a clear coating material.

[0002]

2. Description of the Related Art Organic solvent type hydrophilic coloring paints,
A method of applying a water-based coloring paint and a clear paint to form a multilayer coating film is already known. The uncured coating film of the organic solvent type hydrophilic coating material has strong water absorption, and when the coating surface is coated with the water-based coloring coating material, the water content in the coating film is absorbed and the viscosity sharply increases. Even when this water-based coloring paint is applied in a low humidity atmosphere, there is an effect that defects such as rough skin do not occur. Further, even when an aqueous metallic paint is used as the aqueous colored paint, it is possible to form an excellent metallic luster and excellent gloss clarity without being affected by humidity at the time of application. On the other hand, the coating film of the organic solvent-type hydrophilic coloring coating material should have low light transmittance, excellent concealing properties, and be as thin as possible in order to maintain the weather resistance and aesthetics of the multilayer coating film. Preferably, for this purpose, a large amount of a coloring pigment has been contained so far. As a result, the concealing property can be ensured, but on the other hand, there is a defect that the physical performance of the coating film is apt to decrease.

[0003]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a method for forming a multilayer coating film by applying an organic solvent type hydrophilic coloring paint, an aqueous coloring paint and a clear paint. Without sacrificing excellent performance,
It is to eliminate defects.

In such a method for forming a multi-layer coating film, there is a keen need for a method in which the content of the coloring pigment in the hydrophilic coloring paint is low, and even if the coating film is thin, the concealing property is excellent and the physical performance of the coating film is not reduced. Researched. As a result, it has been found that the object can be achieved by adding a specific amount of aluminum powder having an average particle diameter in a specific range to the hydrophilic coloring paint together with the coloring pigment, and completed the present invention.

Thus, according to the present invention, an organic solvent type hydrophilic coating material (A), an aqueous coloring coating material (B) and a clear coating material (C) are applied to an object to be coated, and these coating films are heated and heated. A hydrophilic paint (A)
Contains a neutralized product of a carboxyl group-containing resin having an acid value of 5 to 100, a curing agent, an aluminum powder having an average particle diameter of 20 μm or less, and a coloring pigment, and the content of the aluminum powder is 100% by weight of the resin solid content. A method for forming a multilayer coating film is provided, wherein the amount is 0.1 to 10 parts by weight per part.

In the method of the present invention, when the aqueous colored coating (B) is applied to the uncured coating surface of the organic solvent type hydrophilic coating (A), the neutralized coating contained in the coating of the hydrophilic coating (A) is neutralized. Since the carboxyl group-containing resin shows strong water absorption, the water in the coating film of the water-based coloring paint (B) applied on the coated surface is absorbed, and the viscosity increases sharply. Even when painted in a low humidity atmosphere, defects such as rough skin rarely occur. Further, when a metallic paint is used as the water-based colored paint (B), it is possible to form a metallic luster free and excellent gloss glossiness without being affected by humidity at the time of painting. In addition, by including a specific amount of aluminum powder having an average particle diameter in a specific range together with the color pigment in the hydrophilic color paint (A), even if the content of the color pigment is small, a thin film and excellent concealing properties can be obtained. Further, it was found that the physical performance of the coating film was not reduced.

Hereinafter, the coating method of the present invention will be described in more detail.

[0008] Examples of the object to be formed by the coating method of the present invention to form a multilayer coating film include metal products and plastic products. Passenger cars, trucks, Examples include automobile bodies such as motorcycles and buses. It is preferable that these objects to be coated are previously subjected to a surface treatment by an appropriate means.

The organic solvent type hydrophilic paint (A) can be applied directly to these objects to be coated. However, an undercoat such as a cationic electrodeposition paint and, if necessary, an intermediate coat are applied. After the respective coating films are cured, it is preferable to apply the hydrophilic paint (A). Known undercoating and intermediate coatings can be used.

The organic solvent type hydrophilic coating material (A) is applied directly to an object to be coated or an undercoating agent, and further, if necessary, an intermediate coating agent, and the coating surface is formed by curing these coating films. The paint to be painted.

Specifically, a neutralized product of a carboxyl group-containing resin having an acid value of 5 to 100, a curing agent, and an average particle diameter of 20 μm
m or less of an aluminum powder and a coloring pigment, and the content of the aluminum powder is 0.1 to 10 parts by weight per 100 parts by weight of resin solid content.

An acid value of 5 used in the hydrophilic paint (A)
As the carboxyl group-containing resin having 100, various known resins can be used as long as such requirements are satisfied. Typical examples thereof include the following resins.

(I) at least one of the following carboxyl group-containing polymerizable monomers in group (a) and at least one polymerizable monomer in group (c) copolymerizable therewith, if necessary (B) a number average molecular weight of about 3,000 to about 4 obtained by copolymerizing at least one of the hydroxyl group-containing polymerizable monomers of the group;
0000 acrylic resin or vinyl resin.

Group (a): α, β-ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid and crotonic acid.

Group (b): 2-hydroxyethyl (meth)
(Meth) acrylic acid, such as acrylate and hydroxypropyl (meth) acrylate, having 1 to 8 carbon atoms.

Group (c): methyl (meth) acrylate,
Ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Lauryl (meth) acrylate, stearyl (meth) acrylate, alkyl or cycloalkyl esters of (meth) acrylic acid having 1 to 24 carbon atoms, such as decyl acrylate; (meth) acrylamide, N-methyl (meth) acrylamide , N-ethyl (meth) acrylamide, diacetone acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl acrylamide and the like; (meth) acrylamide; glycidyl (meth) acrylate, glycidyl (meth) acrylamide, allyl glycidyl ether and the like Glycidyl group-containing vinyl monomer; styrene, vinyl toluene, vinyl propionate, α-methylstyrene, vinyl acetate, (meth)
Vinyl monomers such as acrylonitrile, vinyl propionate, vinyl pivalate, and veova monomer (shell chemical products).

(Ii) ethylene glycol, diethylene glycol, propylene glycol, butanediol,
Pentanediol, 2,2-dimethylpropanediol, glycerin, trimethylolpropane, polyhydric alcohols such as pentaerythritol, and monoepoxy compounds having one glycidyl group in the molecule or monohydric alcohol used in combination as necessary, For example, Khajura E (trade name, product of Shell Chemical Co., Ltd.) is used as an alcohol component,
Polybasic acids such as phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, succinic anhydride, adipic acid, sebacic acid, trimellitic anhydride, pyromellitic anhydride, and as needed Oil-free alkyd resin obtained by condensing a monobasic acid such as benzoic acid or t-butylbenzoic acid used as an acid component together with these components; castor oil, tung oil, sa An oil-modified alkyd resin obtained by reacting using an oil component that is one or a mixture of two or more of these oils, such as flower oil, soybean oil, linseed oil, tall oil, coconut oil, The number average molecular weight is suitably in the range of 500 to 10,000.

(Iii) A graft copolymer obtained by grafting an acrylic resin or a vinyl resin onto an alkyd resin. The number average molecular weight is preferably about 5,000 to about 40,000, and is obtained, for example, by reacting the above polymerizable monomer with an alkyd resin having a polymerizable unsaturated group.

The acid value of these carboxyl group-containing resins is 5 to 100, preferably 10 to 50, and more preferably 3 to 50.
It is in the range of 0-50. When the acid value of this resin is less than 5, the compatibility with the aqueous coloring paint (B) applied to the coated surface of the organic solvent type hydrophilic paint (A) containing the resin becomes poor, and the resin is contained in the coating film. Since the ability to absorb moisture is reduced, defects such as uneven flow of the coating (B) and sagging occur, and the aesthetics of the coating film deteriorates. Also, the acid value is 100
If it is larger, the water resistance of the coating film itself of the hydrophilic coating material (A) deteriorates, which is not preferable.

In the carboxyl group-containing resin, a hydroxyl group can coexist with the carboxyl group by, for example, copolymerizing the hydroxyl group-containing polymerizable monomer of the group (b). It is preferable that such both functional groups coexist because the hardness, water resistance, weather resistance and the like of the coating film are improved. Its hydroxyl value is from about 10 to about 200, in particular 25
It is preferably in the range of 70 to 70.

Examples of the neutralizing agent for neutralizing the carboxyl group-containing resin include ammonia, methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, dimethylethanolamine, diethanolamine and triethanolamine. Basic substances can be used. The amount of the neutralizing agent to be used is preferably about 0.1 to about 2.0 equivalents, particularly preferably about 0.3 to about 1.2 equivalents to the carboxyl group.

The curing agent used in the organic solvent type hydrophilic coating material (A) is effective for crosslinking and curing the coating film.
For example, an amino resin, a block polyisocyanate compound and the like can be mentioned.

As the amino resin, for example, melamine,
Examples include a condensation or co-condensation product of benzoguanamine, a triazine compound, urea, dicyandiamide, and the like with formaldehyde, and a melamine formaldehyde resin is particularly preferable. An alkyl etherified amino resin obtained by reacting these condensates with a monoalcohol having 1 to 8 carbon atoms is preferably used.

The block polyisocyanate compound is a compound in which the isocyanate group of the polyisocyanate compound is blocked by a blocking agent. When the blocking agent is heated to the dissociation temperature of the blocking agent (for example, about 100 to 170 ° C.), the blocking agent is removed. Upon dissociation, the isocyanate group is freely regenerated and can react with the crosslinkable functional group.

The polyisocyanate compound is a compound having two or more isocyanate groups in one molecule, for example, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene. Aromatic diisocyanate such as diisocyanate, aliphatic methylene diisocyanate such as tetramethylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate and lysine diisocyanate; Methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane diisocyanate
Alicyclic diisocyanates such as cyclohexanediisocyanate and cyclopentanediisocyanate, and the biuret type, isocyanuric ring type, and polyols of these polyisocyanate compounds. And a free isocyanate group-containing prepolymer. Blocking agents include phenols, oximes, lactams, active methylenes, alcohols, acid amides, imides, amines, imidazoles, ureas, carbamic acids, imines, mercaptans And the like. The molecular weight of the block polyisocyanate compound is preferably in the range from about 200 to about 10,000.

The compounding ratio of the carboxyl group-containing resin and the curing agent is such that the carboxyl group-containing resin is about 50 to about 90%, preferably about 60%, based on the total solid weight of both.
It is suitable to use from about 10 to about 50%, preferably from about 15 to about 40%, of the curing agent.

The organic solvent type hydrophilic coating material (A) contains, in addition to the above neutralized product of the carboxyl group-containing resin and the curing agent, an aluminum powder having an average particle size of 20 μm or less and a coloring pigment.

The aluminum powder is scaly metallic aluminum having an average particle size of 20 μm or less, especially 1 μm.
A range of 5 to 5 μm is preferred. If it is larger than 20 μm, the smoothness of the coated surface is lowered, which is not preferable. Here, the “average particle size” refers to a laser diffraction scattering method (LA-50).
0) means the median diameter. The thickness is suitably 0.001 to 0.5 μm. A suitable mixing ratio of the aluminum powder is, for example, 0.1 to 10 parts by weight, particularly 1 to 5 parts by weight, per 100 parts by weight of the resin solids.

A coating film obtained by mixing aluminum powder having such a size in the above-mentioned ratio was able to remarkably improve the concealing property without showing any glittering glitter. As a result, the amount of the color pigment used in combination can be further reduced, for example, in a system using titanium white pigment alone as the color pigment, the amount can be reduced to about half, As a result, it has become possible to improve the physical performance of the coating film, for example, chipping / peeling resistance (impact resistance). The coloring pigment to be added to the hydrophilic coating material (A) gives the coating film an arbitrary color tone and concealing property. Examples thereof include titanium dioxide, carbon black, phthalocyanine blue, phthalocyanine green, carbazole violet, anthrapyridine, and azo orange. Organic and inorganic coloring pigments such as yellow, flavanthrone yellow, isoindoline yellow, azo yellow, indathrone blue, dibromo anzathrone red, perylene red, azo red, anthraquinone red, quinacridone red, violet, etc., monoazo dyes, Polyazo dyes, metal complex salt azo dyes,
Azo dyes such as pyrazolone azo dyes, stilbene azo dyes and thiazole azo dyes; anthraquinone dyes such as anthraquinone derivatives and anthrone derivatives; indigo dyes such as indigo derivatives and thioindigo derivatives; phthalocyanine dyes; diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, Carbonium dyes such as acridine dyes, azine dyes, oxazine dyes, quinone imine dyes such as thiazine dyes, polymethine (or cyanine) dyes, methine dyes such as adimethine dyes, quinoline dyes, nitro dyes, nitrone dyes, benzoquinones, naphthoquinone dyes, naphthalimides Dyes such as dyes and perinone dyes can be mentioned, and one or more kinds selected from these can be used. The mixing ratio of these coloring pigments is not particularly limited, and they can be mixed within a range in which a coating film having a desired color tone can be formed.

The hydrophilic coating material (A) can be prepared by dissolving or dispersing the neutralized product of the carboxyl group-containing resin, the curing agent, the aluminum powder, and the coloring pigment in an organic solvent. About 35
It is preferable that the so-called high solid type is adjusted to not less than 40% by weight, especially about 40 to about 60% by weight.

Examples of the organic solvent include ester solvents, ether solvents, alcohol solvents, amide solvents, ketone solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic solvents for paints. Hydrocarbon solvents and the like can be mentioned, and one or more selected from these can be used. Among them, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether , Diethylene glycol monobutyl ether, methyl alcohol,
Ethyl alcohol, allyl alcohol, n-propyl alcohol, isopropyl alcohol, tert-butyl alcohol, ethylene glycol, 1,2-propylene glycol and its monoether, 1,3-butylene glycol, 2,3-butylene glycol, hexylene glycol It is preferable to use a hydrophilic organic solvent such as hexanediol, dipropylene glycol and its monoether, acetone, diacetone alcohol and the like. The water solubility of these hydrophilic organic solvents at 20 ° C. is preferably 50 parts by weight or more per 100 parts by weight of water. The proportion of the hydrophilic organic solvent is suitably 20% by weight or more, especially 40 to 100% by weight, based on the total weight of the organic solvent contained in the hydrophilic paint (A) at the time of coating.

Hydrophilic paint (A) containing the above components
Is 10 μm or less, and more preferably 8 to 5 based on the cured coating film without containing a large amount of a coloring pigment.
μm. Here, the background concealability is
The hydrophilic paint (A) is applied to the surface of a black-and-white checkered pattern, and the thickness of the thinnest paint film in which the pattern is not visible through the paint film.

The hydrophilic paint (A) can be applied directly to the object to be coated. However, an undercoat or an intermediate paint such as an electrodeposition paint (anionic or cationic) is applied, and these paint films are applied. It is preferable to paint after curing. As a coating machine, an atomization type is preferable, for example, air spray,
Examples include airless spray and air atomization type or rotary electrostatic coating machines. The viscosity of the hydrophilic coating material (A) at the time of coating is about 15 to about 60 seconds, particularly 15
It is preferably adjusted to 35 seconds (20 ° C.), and the thickness of the coating is preferably larger than the thickness of the underlayer concealment based on the cured coating film, for example, about 5 to about 25 μm.

In the present invention, the object to be coated is coated with the hydrophilic coating material (A), and the coating film is allowed to stand at room temperature for about 1 to 10 minutes if necessary without being cured. It is preferable to apply the aqueous coloring paint (B).

The water-based colored coating (B) is a coating to be applied to the uncured coating surface of the organic solvent-type hydrophilic coating (A), and is a water-based coating using water as its main solvent or dispersion medium. A water-based coloring paint containing a vinyl resin and / or a polyester resin, a curing agent, and a coloring pigment can be preferably used.

As the vinyl resin in the water-based colored coating (B), those known per se can be used. For example, a number average molecular weight of about 3,000 to about 40,000, an acid value of about 2 obtained by copolymerization using a carboxyl group-containing polymerizable monomer, a hydroxyl group-containing polymerizable monomer and other polymerizable monomers.
Acrylic resins and vinyl resins having 0 to about 100 and a hydroxyl value of about 20 to about 200 can be mentioned.

As the carboxyl group-containing polymerizable monomer, monoethylenically unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid and itaconic acid; and as the hydroxyl group-containing polymerizable monomer, (meth) acrylic acid Examples include hydroxyalkyl esters of monoethylenically unsaturated carboxylic acids such as 2-hydroxyethyl and 2-hydroxypropyl (meth) acrylate. Other polymerizable monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) lauryl acrylate, (meth)
Alkyl esters of monoethylenically unsaturated carboxylic acids such as decyl acrylate, (meth) acrylamide, N
-Acrylamide derivatives such as methylol (meth) acrylamide and diacetone acrylamide; glycidyl esters of monoethylenically unsaturated carboxylic acids such as glycidyl (meth) acrylate; vinyl esters of saturated carboxylic acids such as vinyl acetate and vinyl propionate And aromatic unsaturated monomers such as styrene, α-methylstyrene and vinyltoluene.

The acrylic resin thus obtained uses ammonia or amines such as triethylamine, monoethanolamine, diethanolamine, triethanolamine and dimethylaminoethanol, or a basic substance such as an alkali metal hydroxide such as sodium hydroxide. To make it aqueous. Further, with or without using a carboxyl group-containing polymerizable monomer, water is obtained by dispersing a copolymer in water using a hydroxyl group-containing polymerizable monomer and other polymerizable monomers. Dispersions can also be used.

As the aqueous polyester resin, those having an acid value of 15 to 100 and a hydroxyl value of 20 to 200 among the polyester resins exemplified for the hydrophilic coating material (A) can be suitably used.

As a curing agent in the aqueous coloring paint (B), a condensation or cocondensation product of melamine, benzoguanamine, a triazine compound, urea, dicyandiamide and the like with formaldehyde is further modified with a monoalcohol having 1 to 8 carbon atoms. And carboxyl-containing amino resins. Of these, melamine resins etherified with alcohols are particularly preferred. These curing agents can be used irrespective of whether they are hydrophilic or hydrophobic.

The mixing ratio of the vinyl resin and / or the polyester resin and the curing agent in the water-based coloring paint (B) is as follows:
The former component is about 50% based on the total solid weight of both.
To about 90% by weight, preferably about 60 to about 85% by weight, the curing agent component is about 10 to about 50% by weight, preferably about 15 to about 50% by weight.
It is used in the range of about 40% by weight.

The coating film of the water-based coloring paint (B) is colored in a solid color tone, a metallic tone, a light interference tone or the like, and the degree of the coloring is determined by the hydrophilicity adjacent to the lower layer through the coating film. The color of the coating film of the water-soluble paint (A) is either transparent to the extent that it can be seen, or opaque to the extent that it cannot be seen. The solid color tone coating film can be obtained by blending the coloring pigments (including dyes) exemplified for the hydrophilic paint (A). The metallic coating film can be formed by blending a known metallic pigment such as aluminum flake, and the light interference coating film is a scale coated with a metal oxide such as titanium oxide. It can be formed by blending an interference color pigment such as mica powder.

The water-based colored coating (B) can be applied in the same manner as the hydrophilic coating (A). The coating viscosity is about 10 to about 50 seconds (20 ° C.) using a Ford cup # 4. The thickness is preferably about 5 to about 30 μm, particularly about 10 to about 20 μm, based on the heat-cured coating film.

In the method of the present invention, the organic solvent type hydrophilic coating material (A) and the aqueous coloring coating material (B) are applied as described above, and left at room temperature for about 1 to 10 minutes, or
It is preferable to apply a clear paint (C) after preheating at 100 ° C., preferably 60 to 80 ° C. for 1 to 20 minutes.

The clear paint (C) may be pre-coated if necessary.
It is a paint that forms a transparent coating to be applied to the coated surface of the uncured water-based colored coating (B) that has been cured, and has a multi-layer coating film with beautiful makeup, finished appearance, weather resistance, chemical resistance, water resistance, and moisture resistance. Properties and the like can be further improved. Specific examples include organic solvent-type or non-aqueous dispersion type paints using a thermosetting resin composition composed of an acrylic resin (base resin) and an amino resin (crosslinking agent) as a vehicle component. An agent, a colorant, and the like can be appropriately compounded.

The clear paint (C) is preferably of a high solid content type from the viewpoint of preventing pollution and saving resources. Specifically, the non-volatile content at the time of coating is about 35% by weight or more, and preferably about 35% by weight or more. It is preferably adjusted to 40 to about 80% by weight, more preferably to about 45 to about 80% by weight.

The clear paint (C) can be applied in the same manner as the hydrophilic paint (A). The viscosity at the time of application is adjusted to about 15 to about 60 seconds (20 ° C.) with a Ford cup # 4. It is preferable to apply a thickness of about 5 to about 50 μm based on the cured coating film.

In the method for forming a multilayer coating film of the present invention, the above-mentioned hydrophilic coating material (A), water-based coloring coating material (B) and clear coating material (C) are applied repeatedly, and at about 120 to about 180 ° C., about 15 to about 180 ° C. It is obtained by heating and curing for 45 minutes.

[0049]

Advantages of the Invention Organic solvent type hydrophilic coloring paint (A),
In the method of forming a multilayer coating film by applying the aqueous coloring paint (B) and the clear coating (C), the neutralized carboxyl group-containing resin in the hydrophilic coloring paint is hydrophilic, The water-based coloring paint (B) has good compatibility with the water-based coloring paint (B) coated on the surface, and furthermore, the water content in the coating film of the water-based coloring coating (B) is absorbed and the viscosity of the coating film sharply increases. Has the effect of not causing defects such as rough skin even when painted in a low humidity atmosphere.

2. Even if the metallic type aqueous coloring paint (B) is used, it is not affected by the humidity at the time of coating, so that it is possible to form a metallic coating film having no metallic unevenness and excellent gloss clarity. .

3. The organic solvent type hydrophilic paint (A) contains a specific aluminum powder and a coloring pigment. In particular, when a specific amount of the aluminum powder is contained, the coating film has almost no glitter. Without showing, the hiding power can be remarkably improved, so that the amount of the color pigment used in combination can be reduced, and as a result, the physical performance of the coating film of the hydrophilic paint (A), for example, It is possible to improve chipping / peeling properties (impact resistance) and the like.

4. The multilayer coating film formed by the present invention is
It is a coating method that is extremely excellent in finished appearance, design properties, coating workability, etc., and is advantageous in resource saving and pollution control, and can be widely used in coating of automobiles, motorcycles, electric appliances and the like.

[0053]

EXAMPLES The present invention will be described more specifically below with reference to examples and comparative examples. All parts and percentages are based on weight, and the thickness of the coating film is based on the cured coating film.

1. Preparation of sample 1) Coating material a: Electrodeposited “Electron # 9400” (trade name, manufactured by Kansai Paint Co., Ltd., cationic electrodeposition paint) on a steel plate subjected to degreasing and zinc phosphate treatment by a conventional method. 3 at 175 ° C
The coating was cured by heating for 0 minutes. The thickness is 20 μm. Then, apply an intermediate coating "Lugabeque intermediate coating, light gray color" to the coated surface (Kansai Paint Co., Ltd., trade name)
Was coated and heated at 140 ° C. for 30 minutes to cure the coating film (film thickness: 20 μm) to obtain an object to be coated.

2) Organic Solvent-Type Hydrophilic Colored Paint (A) An organic solvent-type hydrophilic colored paint (A) was obtained by mixing based on the components and amounts shown in Table 1. Adjustment of viscosity and solid content was performed by adding isopropyl alcohol.
The compounding amount is the solid content ratio.

[0056]

[Table 1]

(Note 1): 30 parts of methyl methacrylate,
Ethyl acrylate 23 parts, butyl acrylate 30
Parts, hydroxyethyl methacrylate 12 parts and acrylic acid 5 parts were polymerized to obtain an acrylic resin organic solvent solution (solid content 60%) having an acid value of 40, a hydroxyl value of 52 and a number average molecular weight of about 10,000. The solution was neutralized by adding dimethylaminoethanol, and then diluted with isopropyl alcohol (solid content: 50%).

(Note 2): Neopentyl glycol
After 7 mol, 0.3 mol of trimethylolpropane, 0.4 mol of phthalic anhydride and 0.5 mol of adipic acid are subjected to an esterification reaction, 0.03 mol of trimellitic anhydride is added and further reacted. By adding butyl cellosolve, a polyester resin solution having an acid value of 40, a number average molecular weight of about 6,000, and a resin solid content of 70% was obtained. The polyester resin solution was neutralized by adding dimethylaminoethanol, and then diluted with isopropyl alcohol (solid content: 50%). (Note 3): Product name, manufactured by Mitsui Cytec
Water-soluble melamine resin.

(Note 4): Trade name, aluminum paste, manufactured by Toyo Aluminum Co., Ltd. Average particle size 12 μm.

(Note 5): Second / Food cup # 4/20
° C.

(Note 6): The undercoat concealing property is the thickness of the thinnest coating film in which the hydrophilic paint (A) is applied to the surface of a black and white checkered pattern and the pattern is not visible through the coating film.

3) Water-based colored paint (B) A water-based colored paint (B) was obtained by mixing based on the components and amounts shown in Table 2. Adjustment of viscosity and solid content was made by adding deionized water. The compounding amount is the solid content ratio.

[0063]

[Table 2]

(Note 7): 140 parts of deionized water, 30%
2.5 parts of "Newcol 707SF" (surfactant, trade name, manufactured by Nippon Emulsifier Co., Ltd.) and 1 part of the following monomer mixture (1) are added, and the mixture is stirred and mixed in a nitrogen gas stream.
C., and 3 parts of a 3% aqueous solution of ammonium persulfate were added. Then, after raising the temperature to 80 ° C., 79 parts of the monomer mixture (1), 2.5 parts of “Newcol 707SF” 2.5
Of a 3% aqueous solution of ammonium persulfate and 42 parts of deionized water were added to the reaction vessel over 4 hours. Thereafter, aging was performed for 1 hour. In addition, 80
At 0.5 ° C., 20.5 parts of the following monomer mixture (2) and 4 parts of a 3% ammonium persulfate aqueous solution were simultaneously added dropwise to the reaction vessel over 1.5 hours. After aging for 1 hour, deionized water 3
Diluted with 0 parts. Deionized water was added to the filtrate, and the pH was adjusted to 7.5 with dimethylaminoethanol to obtain an acrylic resin emulsion having a solid content of 20%.

Monomer mixture (1): 55 parts of methyl methacrylate, 8 parts of styrene, 9 parts of n-butyl acrylate
Parts, 2-hydroxyethyl acrylate 5 parts 1,6-hexanediol diacrylate 2 parts, methacrylic acid 1 part Monomer mixture (2): methyl methacrylate 5 parts, n-butyl acrylate 7 parts, acrylic acid 2 -Ethylhexyl 5 parts, methacrylic acid 3 parts, "Newcol 7
07SF ”0.5 parts (Note 8) Aluminum paste 891K: trade name, manufactured by Toyo Aluminum Co., Ltd.

4) Clear paint (C) (C-1) 57 parts of acrylic resin solution (Note 9), 50 parts of non-aqueous dispersion of acrylic resin (Note 10), Cymel 303
(Note 11) A mixture consisting of 30 parts, 4 parts of a 25% dodecylbenzenesulfonic acid solution, and 0.5 parts of BYK-300 (Note 12) was mixed with Swazol # 1000 (trade name, manufactured by Cosmo Oil Co., Ltd., aromatic hydrocarbon solvent). ) To adjust the viscosity to 30 seconds (Ford cup # 4/20 ° C.) to obtain a clear coat (C-1) having a resin solid content of 55%.

(Note 9) Acrylic resin solution: 40 parts of “Swazol # 1000” was added to a reaction vessel and heated to 120 ° C., whereupon 30 parts of styrene, 35 parts of butyl acrylate, and 10 parts of 2-ethylhexyl acrylate were added. A monomer mixture consisting of 25 parts of hydroxyethyl acrylate and 4 parts of α, α'-azobisisobutyronitrile
A resin obtained by adding and polymerizing over time, and having a hydroxyl value of 1
20, number average molecular weight about 6,000, resin solid content 70%.

(Note 10) Acrylic resin non-aqueous dispersion: 58 parts of Uban 28-60 (trade name, melamine resin solution, solid content 60%, manufactured by Mitsui Toatsu Chemicals, Inc.) in a reaction vessel, n-part
30 parts of heptane and 0.15 part of benzoyl peroxide were charged and heated to 95 ° C.
5 parts, acrylonitrile 9 parts, methyl methacrylate 13 parts, methyl acrylate 15 parts, n-butyl acrylate 1.8 parts, 2-hydroxyethyl methacrylate 10 parts, acrylic acid 1.2 parts, benzoyl peroxide 0.5 parts, n 5 parts of butanol, 30 parts of “Shellsol 140” (trade name, manufactured by Shell Sekiyu KK),
A monomer mixture consisting of 9 parts of n-heptane was added dropwise over 3 hours. One hour later, 0.65 parts of t-butyl peroctoate, "Shellsol 140"
3.5 parts were added dropwise over 1 hour. Thereafter, stirring was continued for 2 hours while maintaining a temperature of 95 ° C., and the solvent was removed under reduced pressure to obtain an acrylic resin non-aqueous dispersion having a resin solid content of 60% and a varnish viscosity A (Gardner bubble viscosity).

(Note 11) Cymel 303: trade name, manufactured by Mitsui Cytec, a monomeric melamine resin.

(Note 12) BYK-300: manufactured by BYK Japan KK, trade name, surface conditioner.

2. Examples and Comparative Examples The hydrophilic colored paints (A-1) to (A-4) were applied to an object to be coated at a relative humidity of 75% RH with a film thickness of 10 μm by air spray and left at room temperature for about 5 minutes. Then, the aqueous cured paints (B-1) to (B-2) were applied to the uncured coating film surface at a relative humidity of 75% RH to a film thickness of about 15 μm by air spray, and pre-pressed at 60 ° C. for 5 minutes. After that, the clear paint (C-1) was applied by air spray to a film thickness of 35 μm, left at room temperature for about 5 minutes, and then heated at 140 ° C. for 30 minutes to simultaneously cross-link and cure the three-layer coating film. . Table 3 shows these coating steps and the performance test results of the obtained multilayer coating film.

[0072]

[Table 3]

Test Method Smoothness: Measured with a tension meter (manufactured by RENAULY). The higher the value, the better the smoothness.

Sharpness: Sharpness was measured by NSIC (manufactured by Suga Test Instruments Co., Ltd.). The higher the value, the better the sharpness.

Water resistance: 240 g of the sample coated plate in warm water of 40 ° C.
After immersion for a time, the state of the coated surface was visually evaluated according to the following criteria. ：: No abnormality is observed, Δ: Slight defects such as glossiness and blistering are observed, ×: Defects such as glossiness and blistering are remarkable.

Water adhesion: A sample coated plate was placed in warm water of 40 ° C.
After immersion for 0 days, the coating film was dried, and the coated surface was cut with a cutter knife at 11 mm intervals at 2 mm intervals so as to reach the substrate. Make 100 2mm Gobang eyes,
At 20 ° C., an adhesive cellophane tape was adhered to the coated surface, and after rapidly peeling it off, the number of remaining rub-off coated films was examined.
：: 100 remained, Δ: 99 to 90 remained,
X: 89 or less remained.

Impact resistance: JIS K-5400
3.2 (1990). Point radius 6.3m
A 500 g weight was dropped from a height of 30 cm using a m-type shooting mold, and the coating was visually observed for cracking and peeling. ：: Cracks and peeling were not observed at all. Δ: Cracks and peeling occurred partially at the drop point and its surroundings. ×: Significant cracks and peeling occurred at the falling point and its surroundings.

Chipping resistance: QGR gravelomer
4 kg of No. 7 crushed stone using
g / cm ² air pressure. Crushed stones were sprayed on the test plate at a temperature of 20 ° C. to give an impact to the coating film.
The salt spray test was carried out for 48 hours according to the method specified in 371. The state of rust generation was comprehensively evaluated and displayed according to the following criteria. ：: excellent (2 or less rust generated on a 7 cm × 7 cm test plate), Δ: slightly poor (3 to 9 rust generated on a 7 cm × 7 cm test plate), ×: poor (7 cm × 7 cm)
No. 10 or more rusts are shown on the test plate.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 7/12 C09D 7/12 Z F-term (Reference) 4D075 BB26Z CA37 CA47 DC12 EA06 EA43 EB55 EC02 EC10 EC11 EC53 4J038 CG011 CG031 CG061 CG071 CG081 EA011 GA06 HA066 KA03 PA07 PA19

Claims (1)

[Claims] 1. A multi-layer coating film in which an organic solvent type hydrophilic coating material (A), an aqueous coloring coating material (B) and a clear coating material (C) are applied to an object to be coated and heated to cure these coating films. In the forming method, the hydrophilic paint (A) has an acid value of 5 to 10;
A neutralized carboxyl group-containing resin, a curing agent, an aluminum powder having an average particle size of 20 μm or less and a coloring pigment, and the content of the aluminum powder is 1
0.1 to 10 parts by weight per 100 parts by weight.